Slide fasteners are well known. A conventional slide fastener comprises a pair of stringers (referred to collectively as a chain) and an opening and closing means referred to as a slider. Each stringer comprises a tape, a cord and a plurality of coupling elements. The tape may be knitted, woven or formed of a non-woven material. The coupling elements extend along one edge of each tape, and when the slide fastener is in a closed configuration the coupling elements on one tape co-operate in an interdigitating relationship with the coupling elements on the second tape so as to secure the first and second tapes together. Consequently, when each tape of the slide fastener is attached to a piece of material, the pieces of material may be joined by closing the slide fastener using the slider, thereby bringing the coupling elements into the interdigitating relationship.
As the slider moves as it opens and closes the slide fastener, it is necessary to ensure that the slider cannot move beyond the teeth and possibly detach from the slide fastener. For this reason stops, selected from a variety known in the art, may be provided at one or more ends of the slide fastener.
Stops that are provided to prevent the slider sliding off the slide fastener when the slider is moved in a direction to close the slide fastener are called top stops, whilst stops that are provided to prevent the slider sliding off the slide fastener when the slider is moved in a direction to open the slide fastener are called bottom stops. A slide fastener including a bottom stop that permanently secures both tapes of the fastener together is known as a closed end slide fastener. A slide fastener including a bottom stop that comprises a two-part bottom stop (e.g., a box and a pin, but not limited to this), which releasably attaches the first tape to the second tape, is known as an open end slide fastener. Each part of the two-part bottom stop is secured to a respective tape. The two parts of the bottom stop co-operate so that when the slide fastener is closed the bottom stop secures the tapes of the slide fastener together.
Due to their versatility, slide fasteners are employed in a wide range of applications including clothing, luggage, home furnishings and upholstery.
The versatility of slide fasteners also means that they are used with a variety of materials ranging from hardwearing denim and cotton to lightweight silks and polyester.
It is common for slide fasteners to be mass-produced. In such mass production methods the tape (or chains) of multiple slide fasteners may be produced in continuous lengths. This means that during the manufacturing process the tape (or chain) of each slide fastener will need to be cut to the length desired by the manufacturer. Whilst there are a variety of methods to cut the tape, in a large number of cases, cutting the tape raises the possibility that the tape will fray from the cut.
To minimise fraying of the tape it is commonplace to attach a piece of reinforcing material (such as taffeta, nylon or other such material) to the cut region at one end or both ends of the tapes of an open end slide fastener.
Another known option for minimising fraying is for a section of tape which continues beyond the coupling elements to be provided beyond the top stop of the slide fastener. Such a section is commonly referred to as an ‘elongate region’ or ‘extension portion’. The extra length is used to attach the slide fastener more securely, simply because there is more material to attach, but this extra length also delays the effects of fraying because if some of this material frays, it will have very little to no effect on the function of the slide fastener once attached.
The use of additional reinforcing material adds weight and depth to the slide fastener. For a large number of items the reinforced tapes do not cause a problem. However, for lightweight material, when the slide fastener is sewn into place the reinforcing material leads to a bulky appearance which spoils the overall aesthetic appearance of a garment to which the slide fastener is applied.
In addition, for wider slide fasteners, the width of the reinforcing material may be limited, with the effect that it may not be straightforward to cover the entire width of the tape with the reinforcing material. As such, fraying may occur at portions of the tape of a slide fastener which is not covered by reinforcing material.
When applying a slide fastener to a garment, folding back the elongate region so that it overlaps with the remaining portion of the respective tape will double the thickness of the tape and create a bulky region.
When using lightweight material, it is known to fold the elongate region at an angle to the coupling elements so that the elongate region protrudes perpendicularly to the direction of the coupling elements. The elongate region is then sewn into the item to which it is to be attached.
However, with lightweight material, a double-thickness folded portion of tape or an angled folded elongate region may still create an extra thickness which may make the garment appear unnecessarily bulky. Additionally, when the tape is wide, folding the tape back in this manner creates a large folded area.
Consequently, for items made of lightweight material, such as for example in eveningwear and sportswear, it is desirable to use slide fasteners made with tapes of reduced thickness to achieve a garment with a smooth appearance when the slide fastener is sewn into place. For some materials however, especially for sportswear, using lightweight stringers (i.e. stringers including tape of reduced thickness) may lead to a garment in which either the slide fastener is prone to detaching, or, may result in a garment in which the overall aesthetic appearance is compromised due to the tapes still being too thick.
Additionally, when an open end slide fastener is used, it is common that the bottom stop of the slide fastener will be in line with an edge of the article to which it is attached. In many cases when the article contains a hem or sewing line at its edge, for example in a garment, the tape adjacent the bottom stop will have a different appearance to the edge of the article and create an incongruency in the visual and tactile aspects of the article.